The game would have to be ported some way or rewritten from the ground up in unity.

Plus, given all the console like controls, it would be developed as a separate platform, most likely, and thus players would have to start from scratch in their own queues.

Cost benefit is not there to throw resources at it, when smartphones and tablets are all over the place.

What are you talking about? You can use a controller on WoT Blitz can you not? What would be so different about porting it to the Switch? The Switch even runs on a mobile card, so all of your excuses are just excuses for Wargaming to be lazy. You wouldn't have to rewrite the entire games code.